The neuroanatomical bases of memory are examined with special reference to the role of the hippocampus is a short-term memory process called working memory. The behavioral experiments establish tasks which have different memory requirements. Then lesion techniques and electrophysiological recording techniques are used to examine hippocampal function. The behavioral tasks are designed to test different types of memory abilities (working memory or reference memory), and to require different types of strategies when moving through space (spatial cognitive mapping or nonspatial nonmapping). Lesions are made in the hippocampal system with either radiofrequency current or with kainic acid. The latter substance selectively destroys the CA3 subfield of the hippocampus, leaving other subfields intact. Single units in the hippocampus are recorded with a moveable microelectrode while rats are performing working memory tasks. The activity of the units is correlated with the behavior of the rats in these tasks.